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<a name="glib-Warnings-and-Assertions"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="glib-Warnings-and-Assertions.top_of_page"></a>Warnings and Assertions</span></h2>
<p>Warnings and Assertions</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="glib-Warnings-and-Assertions.functions"></a><h2>Functions</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-print" title="g_print ()">g_print</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>
</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-set-print-handler" title="g_set_print_handler ()">g_set_print_handler</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<span class="c_punctuation">(</span><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()">*GPrintFunc</a><span class="c_punctuation">)</span> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-printerr" title="g_printerr ()">g_printerr</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>
</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-set-printerr-handler" title="g_set_printerr_handler ()">g_set_printerr_handler</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-fail" title="g_return_if_fail()">g_return_if_fail</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-fail" title="g_return_val_if_fail()">g_return_val_if_fail</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name"><a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-reached" title="g_return_if_reached">g_return_if_reached</a></td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-reached" title="g_return_val_if_reached()">g_return_val_if_reached</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-warn-if-fail" title="g_warn_if_fail()">g_warn_if_fail</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name"><a class="link" href="glib-Warnings-and-Assertions.html#g-warn-if-reached" title="g_warn_if_reached">g_warn_if_reached</a></td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-query" title="g_on_error_query ()">g_on_error_query</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-stack-trace" title="g_on_error_stack_trace ()">g_on_error_stack_trace</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name"><a class="link" href="glib-Warnings-and-Assertions.html#G-BREAKPOINT:CAPS" title="G_BREAKPOINT">G_BREAKPOINT</a></td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="glib-Warnings-and-Assertions.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include &lt;glib.h&gt;
</pre>
</div>
<div class="refsect1">
<a name="glib-Warnings-and-Assertions.description"></a><h2>Description</h2>
</div>
<div class="refsect1">
<a name="glib-Warnings-and-Assertions.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="g-print"></a><h3>g_print ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
g_print (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *format</code></em>,
         <em class="parameter"><code>...</code></em>);</pre>
<p>Outputs a formatted message via the print handler.
The default print handler simply outputs the message to stdout, without
appending a trailing new-line character. Typically, <em class="parameter"><code>format</code></em>
 should end with
its own new-line character.</p>
<p>g_print() should not be used from within libraries for debugging
messages, since it may be redirected by applications to special
purpose message windows or even files. Instead, libraries should
use <a class="link" href="glib-Message-Logging.html#g-log" title="g_log ()"><code class="function">g_log()</code></a>, <a class="link" href="glib-Message-Logging.html#g-log-structured" title="g_log_structured ()"><code class="function">g_log_structured()</code></a>, or the convenience macros <a class="link" href="glib-Message-Logging.html#g-message" title="g_message()"><code class="function">g_message()</code></a>,
<a class="link" href="glib-Message-Logging.html#g-warning" title="g_warning()"><code class="function">g_warning()</code></a> and <a class="link" href="glib-Message-Logging.html#g-error" title="g_error()"><code class="function">g_error()</code></a>.</p>
<div class="refsect3">
<a name="g-print.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>format</p></td>
<td class="parameter_description"><p>the message format. See the <code class="function">printf()</code> documentation</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p>the parameters to insert into the format string</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-set-print-handler"></a><h3>g_set_print_handler ()</h3>
<pre class="programlisting"><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>
g_set_print_handler (<em class="parameter"><code><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="type">GPrintFunc</span></a> func</code></em>);</pre>
<p>Sets the print handler.</p>
<p>Any messages passed to <a class="link" href="glib-Warnings-and-Assertions.html#g-print" title="g_print ()"><code class="function">g_print()</code></a> will be output via
the new handler. The default handler simply outputs
the message to stdout. By providing your own handler
you can redirect the output, to a GTK+ widget or a
log file for example.</p>
<div class="refsect3">
<a name="g-set-print-handler.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>func</p></td>
<td class="parameter_description"><p>the new print handler</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="g-set-print-handler.returns"></a><h4>Returns</h4>
<p> the old print handler</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="GPrintFunc"></a><h3>GPrintFunc ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
<span class="c_punctuation">(</span>*GPrintFunc<span class="c_punctuation">)</span> (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
<p>Specifies the type of the print handler functions.
These are called with the complete formatted string to output.</p>
<div class="refsect3">
<a name="GPrintFunc.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>string</p></td>
<td class="parameter_description"><p>the message to output</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-printerr"></a><h3>g_printerr ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
g_printerr (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *format</code></em>,
            <em class="parameter"><code>...</code></em>);</pre>
<p>Outputs a formatted message via the error message handler.
The default handler simply outputs the message to stderr, without appending
a trailing new-line character. Typically, <em class="parameter"><code>format</code></em>
 should end with its own
new-line character.</p>
<p>g_printerr() should not be used from within libraries.
Instead <a class="link" href="glib-Message-Logging.html#g-log" title="g_log ()"><code class="function">g_log()</code></a> or <a class="link" href="glib-Message-Logging.html#g-log-structured" title="g_log_structured ()"><code class="function">g_log_structured()</code></a> should be used, or the convenience
macros <a class="link" href="glib-Message-Logging.html#g-message" title="g_message()"><code class="function">g_message()</code></a>, <a class="link" href="glib-Message-Logging.html#g-warning" title="g_warning()"><code class="function">g_warning()</code></a> and <a class="link" href="glib-Message-Logging.html#g-error" title="g_error()"><code class="function">g_error()</code></a>.</p>
<div class="refsect3">
<a name="g-printerr.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>format</p></td>
<td class="parameter_description"><p>the message format. See the <code class="function">printf()</code> documentation</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p>the parameters to insert into the format string</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-set-printerr-handler"></a><h3>g_set_printerr_handler ()</h3>
<pre class="programlisting"><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>
g_set_printerr_handler (<em class="parameter"><code><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="type">GPrintFunc</span></a> func</code></em>);</pre>
<p>Sets the handler for printing error messages.</p>
<p>Any messages passed to <a class="link" href="glib-Warnings-and-Assertions.html#g-printerr" title="g_printerr ()"><code class="function">g_printerr()</code></a> will be output via
the new handler. The default handler simply outputs the
message to stderr. By providing your own handler you can
redirect the output, to a GTK+ widget or a log file for
example.</p>
<div class="refsect3">
<a name="g-set-printerr-handler.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>func</p></td>
<td class="parameter_description"><p>the new error message handler</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="g-set-printerr-handler.returns"></a><h4>Returns</h4>
<p> the old error message handler</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-return-if-fail"></a><h3>g_return_if_fail()</h3>
<pre class="programlisting">#define             g_return_if_fail(expr)</pre>
<p>Verifies that the expression <em class="parameter"><code>expr</code></em>
, usually representing a precondition,
evaluates to <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS" title="TRUE"><code class="literal">TRUE</code></a>. If the function returns a value, use
<a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-fail" title="g_return_val_if_fail()"><code class="function">g_return_val_if_fail()</code></a> instead.</p>
<p>If <em class="parameter"><code>expr</code></em>
 evaluates to <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS" title="FALSE"><code class="literal">FALSE</code></a>, the current function should be considered to
have undefined behaviour (a programmer error). The only correct solution
to such an error is to change the module that is calling the current
function, so that it avoids this incorrect call.</p>
<p>To make this undefined behaviour visible, if <em class="parameter"><code>expr</code></em>
 evaluates to <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS" title="FALSE"><code class="literal">FALSE</code></a>,
the result is usually that a critical message is logged and the current
function returns.</p>
<p>If G_DISABLE_CHECKS is defined then the check is not performed.  You
should therefore not depend on any side effects of <em class="parameter"><code>expr</code></em>
.</p>
<div class="refsect3">
<a name="g-return-if-fail.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>expr</p></td>
<td class="parameter_description"><p>the expression to check</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-return-val-if-fail"></a><h3>g_return_val_if_fail()</h3>
<pre class="programlisting">#define             g_return_val_if_fail(expr,val)</pre>
<p>Verifies that the expression <em class="parameter"><code>expr</code></em>
, usually representing a precondition,
evaluates to <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS" title="TRUE"><code class="literal">TRUE</code></a>. If the function does not return a value, use
<a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-fail" title="g_return_if_fail()"><code class="function">g_return_if_fail()</code></a> instead.</p>
<p>If <em class="parameter"><code>expr</code></em>
 evaluates to <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS" title="FALSE"><code class="literal">FALSE</code></a>, the current function should be considered to
have undefined behaviour (a programmer error). The only correct solution
to such an error is to change the module that is calling the current
function, so that it avoids this incorrect call.</p>
<p>To make this undefined behaviour visible, if <em class="parameter"><code>expr</code></em>
 evaluates to <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS" title="FALSE"><code class="literal">FALSE</code></a>,
the result is usually that a critical message is logged and <em class="parameter"><code>val</code></em>
 is
returned from the current function.</p>
<p>If G_DISABLE_CHECKS is defined then the check is not performed.  You
should therefore not depend on any side effects of <em class="parameter"><code>expr</code></em>
.</p>
<div class="refsect3">
<a name="g-return-val-if-fail.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>expr</p></td>
<td class="parameter_description"><p>the expression to check</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>val</p></td>
<td class="parameter_description"><p>the value to return from the current function
if the expression is not true</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-return-if-reached"></a><h3>g_return_if_reached</h3>
<pre class="programlisting">#define             g_return_if_reached()</pre>
<p>Logs a critical message and returns from the current function.
This can only be used in functions which do not return a value.</p>
</div>
<hr>
<div class="refsect2">
<a name="g-return-val-if-reached"></a><h3>g_return_val_if_reached()</h3>
<pre class="programlisting">#define             g_return_val_if_reached(val)</pre>
<p>Logs a critical message and returns <em class="parameter"><code>val</code></em>
.</p>
<div class="refsect3">
<a name="g-return-val-if-reached.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>val</p></td>
<td class="parameter_description"><p>the value to return from the current function</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-warn-if-fail"></a><h3>g_warn_if_fail()</h3>
<pre class="programlisting">#define             g_warn_if_fail(expr)</pre>
<p>Logs a warning if the expression is not true.</p>
<div class="refsect3">
<a name="g-warn-if-fail.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>expr</p></td>
<td class="parameter_description"><p>the expression to check</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<p class="since">Since: <a class="link" href="api-index-2-16.html#api-index-2.16">2.16</a></p>
</div>
<hr>
<div class="refsect2">
<a name="g-warn-if-reached"></a><h3>g_warn_if_reached</h3>
<pre class="programlisting">#define             g_warn_if_reached()</pre>
<p>Logs a warning.</p>
<p class="since">Since: <a class="link" href="api-index-2-16.html#api-index-2.16">2.16</a></p>
</div>
<hr>
<div class="refsect2">
<a name="g-on-error-query"></a><h3>g_on_error_query ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
g_on_error_query (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *prg_name</code></em>);</pre>
<p>Prompts the user with
<code class="literal">[E]xit, [H]alt, show [S]tack trace or [P]roceed</code>.
This function is intended to be used for debugging use only.
The following example shows how it can be used together with
the <a class="link" href="glib-Message-Logging.html#g-log" title="g_log ()"><code class="function">g_log()</code></a> functions.</p>
<div class="informalexample">
  <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
    <tbody>
      <tr>
        <td class="listing_lines" align="right"><pre>1
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        <td class="listing_code"><pre class="programlisting"><span class="gtkdoc ppc">#include &lt;glib.h&gt;</span>

<span class="gtkdoc kwb">static void</span>
<span class="function">log_handler</span> <span class="gtkdoc opt">(</span><span class="gtkdoc kwb">const</span> gchar   <span class="gtkdoc opt">*</span>log_domain<span class="gtkdoc opt">,</span>
             GLogLevelFlags log_level<span class="gtkdoc opt">,</span>
             <span class="gtkdoc kwb">const</span> gchar   <span class="gtkdoc opt">*</span>message<span class="gtkdoc opt">,</span>
             gpointer       user_data<span class="gtkdoc opt">)</span>
<span class="gtkdoc opt">{</span>
  <span class="function"><a href="glib-Message-Logging.html#g-log-default-handler">g_log_default_handler</a></span> <span class="gtkdoc opt">(</span>log_domain<span class="gtkdoc opt">,</span> log_level<span class="gtkdoc opt">,</span> message<span class="gtkdoc opt">,</span> user_data<span class="gtkdoc opt">);</span>

  <span class="function"><a href="glib-Warnings-and-Assertions.html#g-on-error-query">g_on_error_query</a></span> <span class="gtkdoc opt">(</span>MY_PROGRAM_NAME<span class="gtkdoc opt">);</span>
<span class="gtkdoc opt">}</span>

<span class="gtkdoc kwb">int</span>
<span class="function">main</span> <span class="gtkdoc opt">(</span><span class="gtkdoc kwb">int</span> argc<span class="gtkdoc opt">,</span> <span class="gtkdoc kwb">char</span> <span class="gtkdoc opt">*</span>argv<span class="gtkdoc opt">[])</span>
<span class="gtkdoc opt">{</span>
  <span class="function"><a href="glib-Message-Logging.html#g-log-set-handler">g_log_set_handler</a></span> <span class="gtkdoc opt">(</span>MY_LOG_DOMAIN<span class="gtkdoc opt">,</span>
                     G_LOG_LEVEL_WARNING <span class="gtkdoc opt">|</span>
                     G_LOG_LEVEL_ERROR <span class="gtkdoc opt">|</span>
                     G_LOG_LEVEL_CRITICAL<span class="gtkdoc opt">,</span>
                     log_handler<span class="gtkdoc opt">,</span>
                     NULL<span class="gtkdoc opt">);</span>
  <span class="gtkdoc opt">...</span></pre></td>
      </tr>
    </tbody>
  </table>
</div>

<p></p>
<p>If "[E]xit" is selected, the application terminates with a call
to _exit(0).</p>
<p>If "[S]tack" trace is selected, <a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-stack-trace" title="g_on_error_stack_trace ()"><code class="function">g_on_error_stack_trace()</code></a> is called.
This invokes gdb, which attaches to the current process and shows
a stack trace. The prompt is then shown again.</p>
<p>If "[P]roceed" is selected, the function returns.</p>
<p>This function may cause different actions on non-UNIX platforms.</p>
<div class="refsect3">
<a name="g-on-error-query.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>prg_name</p></td>
<td class="parameter_description"><p>the program name, needed by gdb for the "[S]tack trace"
option. If <em class="parameter"><code>prg_name</code></em>
is <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a>, <a class="link" href="glib-Miscellaneous-Utility-Functions.html#g-get-prgname" title="g_get_prgname ()"><code class="function">g_get_prgname()</code></a> is called to get
the program name (which will work correctly if <code class="function">gdk_init()</code> or
<a href="../gtk4/gtk4-General.html#gtk-init"><code class="function">gtk_init()</code></a> has been called)</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-on-error-stack-trace"></a><h3>g_on_error_stack_trace ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
g_on_error_stack_trace (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *prg_name</code></em>);</pre>
<p>Invokes gdb, which attaches to the current process and shows a
stack trace. Called by <a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-query" title="g_on_error_query ()"><code class="function">g_on_error_query()</code></a> when the "[S]tack trace"
option is selected. You can get the current process's program name
with <a class="link" href="glib-Miscellaneous-Utility-Functions.html#g-get-prgname" title="g_get_prgname ()"><code class="function">g_get_prgname()</code></a>, assuming that you have called <a href="../gtk4/gtk4-General.html#gtk-init"><code class="function">gtk_init()</code></a> or
<code class="function">gdk_init()</code>.</p>
<p>This function may cause different actions on non-UNIX platforms.</p>
<div class="refsect3">
<a name="g-on-error-stack-trace.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>prg_name</p></td>
<td class="parameter_description"><p>the program name, needed by gdb for the "[S]tack trace"
option</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="G-BREAKPOINT:CAPS"></a><h3>G_BREAKPOINT</h3>
<pre class="programlisting">#  define G_BREAKPOINT()        G_STMT_START{ __asm__ __volatile__ ("int $03"); }G_STMT_END
</pre>
<p>Inserts a breakpoint instruction into the code.</p>
<p>On x86 and alpha systems this is implemented as a soft interrupt
and on other architectures it raises a <code class="literal">SIGTRAP</code> signal.</p>
</div>
</div>
<div class="refsect1">
<a name="glib-Warnings-and-Assertions.other_details"></a><h2>Types and Values</h2>
</div>
</div>
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